but_calibration_camera_velodyne

ROS packages for extrinsic calibration Velodyne 3D LIDARs(vlp16) with ZED stereo camera. The package follows the methods proposed by:

[1] Velas, Spanel, Materna, Herout: Calibration of RGB Camera with Velodyne LiDAR
[2] Jingfeng Sui, Shuo Wang, Extrinsic Calibration of Camera and 3D Laser Sensor System. pdf

Requirements

roslaunch but_calibration_camera_velodyne calibration_coarse.launch
- command will run the coarse calibration using 3D marker (described in the [1])
- if the 3D marker detection fails, the attempt will be repeated after 5s
- upon the cuccess the node ends and prints the 6 Degrees of Freedom of the Velodyne related to the camera
roslaunch but_calibration_camera_velodyne calibration_fine.launch
- will runs the calibration with the refinement. This process will take a longer time (approx. 1 minute)
roslaunch but_calibration_camera_velodyne coloring.launch
- launches the publisher of colored pointclouds created by the camera -- Velodyne fusion
- the calibration parameters (6DoF) computed by the calibration process must be set in configuration file conf/coloring.yaml (see below)

Configuration *.yaml files are stored in the direcotry conf/:

conf/calibration.yaml contains folowing parameters:
- camera_frame_topic: name of the topic, where camera RGB image is published
- camera_info_topic: topic of CameraInfo type
- velodyne_topic: topic, where the Velodyne pointcloud is published
- marker: physical size of the 3D marker
  - circles_distance: distance between the circles centres (see [1])
  - circles_radius: radius of the circles in marker (also see [1])
in conf/calibration.yaml you can specify:
- 6DoF: vector of the calibration parameters computed by the calibration process
- velodyne_color_topic: name of the topic, where the colored pointcloud will be published